Aaron Braeckel wrote:
IMHO OpenDAP and WCS should be kept largely separate. As stated
elsewhere, the intra-community needs are largely being met with existing
technologies
Hi Aaron,
I'm afraid that this statement over-simplifies the situation. Our
European colleagues ARE (emphatically) part of our community. But many
of them feel that they are mandated to use only OGC-accepted solutions.
So we have a well-defined barrier to intra-community data exchange that
is in need of a solution: one part of the community using OPeNDAP and
another part using WCS. Bringing WCS and OPeNDAP together by carrying
an OPeNDAP URL as a payload in WCS is a remarkably simple and elegant
solution to this problem.
and the real strength of WCS is the broader community.
Standards are always riding a fine balance between flexibility and
standardization, and sacrifices are made to balance on that line.
I would also like to see that NetCDF and OpenDAP be kept separate, as
there are communities of use (including my group) that want to work with
NetCDF but not OpenDAP. Therefore I'm not in favor of a joint NetCDF
and OpenDAP extension profile.
My apologies, but I cannot see the logic of this argument. NetCDF and
OPeNDAP in fact already are very closely coupled and have been so for
many years. Basically (only a slight over-simplification) any
application that can read a netCDF file can read the same data from a
remote host through OPeNDAP (with a relinking of the code at most).
Bringing netCDF and OPeNDAP together (under a WCS umbrella or elsewhere)
does not mandate that both are used by any given community. If you have
reasons to want to avoid the use of OPeNDAP in your community you can
achieve that goal by simply ignoring it.
I think it is worth examining the deeper issues of where data
interoperability barriers come from. It is that we have too many,
narrowly defined standards that cannot talk to one another -- netCDF-CF,
HDF-EOS, geoTIFF, shapefiles, tab-delimited format description or what
have you. Community stovepipes. The heart and sole of the
interoperability effort has to be doing the work necessary to make
standards inter-operate.
The "core plus extensions" philosophy of WCS is fundamentally weak, in
that it solves only the problem of metadata interoperability, data
interoperability remains a collection of stovepipes. Your concerns
above reflect an inevitable consequence that this weakness of WCS has on
clients -- client software must become more complex in order to address
interoperability. Unfortunately this aspect of WCS is a given -- it is
out of our scope to change it.
- Steve
